Push rod puzzels

[tck]

On stripping my MK 4 engine for the first time the RH side contains two 'knitting needle' push rods  while the LH contains two composite push rods of alloy tube with inserted ends each push-rod having one long extended end and one shorter end in addition the inlet push-rod had the long insert towards the engine the exhaust the reverse. I would tend to think the alloy rods are better but one of them is inserted incorectly

[eddie]

The alloy push rods are from a 'Plus' motor.

  Regards,
                Eddie.

[tck]

Any suggestions about the plus push rod end locations? long top or long bottom (top meaning rocker)

[eddie]

Unless someone knows differently, I would think the long end goes to the cam follower (as it sits deeper in the follower than in the rocker arm). Normal steel pushrods from a Mark are radiused the same on both ends, but the rocker end has a head to give that end the full dome - are the 'Plus' rods the same? Perhaps Neville can shed some light??

   Regards,
                  Eddie.

[tck]

Comparing the two types Eddie I think you are correct
Has anyone made Plus pushrods ? I seem to remember reading that a Vincent owner (whose standard push rods are similar but more barrel shaped) made his from arrow shafts whose alloy tubing is extremely strong those Vinny push rods are silver steel and flame harden

[douglas1947]

When I had a Vincent Comet (around 25 - 30 years ago) I used VW Beetle push rods in the engine.
Very similar to the Vincent pushrods and at that time very easy to get.
Unfortunately I have no measures anymore.

Michael

[Neville Heath]

Had a look in one of my oily tins and came up with these.
1 is stationary engine; 2 is I think T35; 3 is Mark; and 4 is Plus.
It might seem strange that Mark and Plus are the same length as the barrels are shorter but that is compensated by the thicker rocker block. Yes the long end goes in the follower. I have often found scrape marks on Plus pusrods where they have rubbed on the tunnels. 
Neville

[Neville Heath]

Push rods





Attachments converted to linked images - Dave, 07Feb2021

[tck]

Thanks Neville i have 3 in the RH and 4 in the LH the engine is a MK4 but someone has spent some time on it.  every day I find something new that is not standard (see my other thread) the carbs are 276 Amals
I have had it for thirty years in my store room slowly coming up my 'to do' list its a MK3 frame from High Wycombe in Bucks  (I found the records and got its original reg no back last year) and a mk4 motor which came from a bike delivered to  Mcandless in NI (the Featherbed men) it was in gold paint and set up as a racer but was in a poor state.